Daniel Yergin ["It's Not the End of the Oil Age," op-ed, July 31] asserted that there will be no problem with world oil supply in the near future. We disagree with his forecast. Moreover, the economic risk associated with relying on such optimism is enormous.

One of us recently completed an intensive study of the oil production capabilities of Saudi Arabia, the linchpin of world oil production. Careful scrutiny of somewhat obscure Saudi technical papers created serious doubts about Saudi claims of adequate supplies of oil for decades to come. The Saudis and OPEC have been quietly admitting that they will not be able to meet world oil demand in 10 to 15 years, which is at odds with Yergin's Cambridge Energy Research Associates and other optimists. The fact that futures prices for oil are above $60 a barrel out to December 2010 is at odds with CERA's position and is a testament to the risks associated with future world oil production.

Why worry if we have 10 to 15 years until oil output peaks? Because we've shown that a maximum worldwide effort to mitigate the shortages and skyrocketing price of oil associated with world peak oil production would have to be started 15 to 20 years before peaking to avoid dire worldwide economic hardship.

The world has never faced a problem like the peaking of world oil production. The stakes for world economies are dire. Being well prepared ahead of oil output peaking, assuming that is still possible, would be infinitely more desirable than risking our economic future on optimistic guesses.

-- Matt Simmons

Houston

-- Robert Hirsch

Alexandria

Matt Simmons is chairman and chief executive of Simmons International and author of "Twilight in the Desert: The Coming Saudi Oil Shock and the World Economy." Robert Hirsch is a consultant in energy and past chairman of the board on energy and environmental systems at the National Academies.